Programmable light beam shape altering device using programmable micromirrors

ABSTRACT

A digital micromirror device (“DMD”) is used to alter the shape of light that is projected onto a stage. The DMD selectively reflects some light, thereby shaping the light that is projected onto the stage. The control for the alteration is controlled by an image. That image can be processed, thereby carrying out image processing effects on the shape of the light that is displayed. One preferred application follows the shape of the performer and illuminates the performer using a shape that adaptively follows the performer&#39;s image. This results in a shadowless follow spot.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of application Ser. No. 11/365,344, Filed Feb.28, 2006, now U.S. Pat. No. 7,515,367, which is a continuation of10/373,412, filed Feb. 24, 2003 now U.S. Pat. No. 7,224,509, which is adivisional of U.S. application Ser. No. 10/197,963, filed Jul. 16, 2002,now U.S. Pat. No. 6,771,411, which is a continuation of U.S. applicationSer. No. 09/928,220, filed Aug. 9, 2001, now U.S. Pat. No. 6,421,165,which is a continuation of U.S. application Ser. No. 09/359,064, filedJul. 21, 1999, now U.S. Pat. No. 6,288,828, which is a divisional ofU.S. application Ser. No. 08/962,237, filed Oct. 31, 1997, now U.S. Pat.No. 5,953,151, which is a divisional of U.S. application Ser. No.08/598,077, filed Feb. 7, 1996, now U.S. Pat. No. 5,828,485.

FIELD OF THE INVENTION

The present invention relates to a programmable light beam shapingdevice. More specifically, the present invention teaches a controlsystem and micromirror device which can alter the shape of light beamspassing therethrough, and provide various effects to those shaped lightbeams.

BACKGROUND OF THE INVENTION

It is known in the art to shape a light beam. This has typically beendone using an element known as a gobo. A gobo element is usuallyembodied as either a shutter or an etched mask. The gobo shapes thelight beam like a stencil in the projected light.

Gobos are simple on/off devices: they allow part of the light beam topass, and block other parts to prevent those other parts from passing.Hence mechanical gobos are very simple devices. Modern laser-etchedgobos go a step further by providing a gray scale effect.

Typically multiple different gobo shapes are obtained by placing thegobos are placed into a cassette or the like which is rotated to selectbetween the different gobos. The gobos themselves can also be rotatedwithin the cassette, using the techniques, for example, described inU.S. Pat. Nos. 5,113,332 and 4,891,738.

All of these techniques, have the drawback that only a limited number ofgobo shapes can be provided. These gobo shapes must be defined inadvance. There is no capability to provide any kind of gray scale in thesystem. The resolution of the system is also limited by the resolutionof the machining. This system allows no way to switch gradually betweendifferent gobo shapes. In addition, moving between one gobo and anotheris limited by the maximum possible mechanical motion speed of thegobo-moving element.

Various patents and literature have suggested using a liquid crystal asa gobo. For example, U.S. Pat. No. 5,282,121 describes such a liquidcrystal device. Our own pending patent application also so suggests.However, no practical liquid crystal element of this type has ever beendeveloped. The extremely high temperatures caused by blocking some ofthis high intensity beam produce enormous amounts of heat. Theprojection gate sometimes must block beams with intensities in excess of10,000 lumens and sometimes as high as 2000 watts. The above-discussedpatent applications discuss various techniques of heat handling.However, because the light energy is passed through a liquid crystalarray, some of the energy must inevitably be stored by the liquidcrystal. Liquid crystal is not inherently capable of storing such heat,and the phases of the liquid crystal, in practice, may be destabilizedby such heat. The amount of cooling required, therefore, has made thisan impractical task. Research continues on how to accomplish this taskmore practically.

It is an object of the present invention to obviate this problem byproviding a digital light beam shape altering device, e.g. a gobo, whichoperates completely differently than any previous device. Specifically,this device embodies the inventor's understanding that many of the heatproblems in such a system are obviated if the light beam shape alteringdevice would selectively deflect, instead of blocking, the undesiredlight.

The preferred mode of the present invention uses a 25digitally-controlled micromirror semiconductor device. However, anyselectively-controllable multiple-reflecting element could be used forthis purpose. These special optics are used to create the desired imageusing an array of smallsized mirrors which are movably positioned. Themicromirrors are arranged in an array that will define the eventualimage. The resolution of the image is limited by the size of themicromirrors: here 17 μm on a side.

The mirrors are movable between a first position in which the light isdirected onto the field of a projection lens system, or a secondposition in which the light is deflected away from the projection lenssystem. The light deflected away from the lens will appear as a darkpoint in the resulting image on the illuminated object. The heat problemis minimized according to the present invention since the micromirrorsreflect the unwanted light rather than absorbing it. The absorbed heatis caused by the quantum imperfections of the mirror and any gapsbetween the mirrors.

A digital micromirror integrated circuit is currently manufactured byTexas Instruments Inc., Dallas, Tex., and is described in “an overviewof Texas Instrument digital micromirror device (DMD) and its applicationto projection displays”. This application note describes using a digitalmicromirror device in a television system. Red, green and blue as wellas intensity grey scales are obtained in this system by modulating themicromirror device at very high rates of speed. The inventor recognizedthat this would operate perfectly to accomplish his objectives.

It is hence an object of the present invention to adapt such a devicewhich has small-sized movable, digitally controllable mirrors which havepositions that can be changed relative to one another, to use as a lightbeam shape altering device in this stage lighting system.

It is another object of the present invention to use such a system forpreviously unheard-of applications. These applications include activesimulation of hard or soft beam edges on the gobo. It is yet anotherapplication of the present invention to allow gobo cross-fading usingtime control, special effects and morphing.

It is yet another object of the present invention to form a stroboscopiceffect with variable speed and intensity in a stage lighting system.This includes simulation of a flower strobe.

Yet another object of the present invention is to provide a multiplecolored gobo system which can have split colors and rotating colors.

It is yet another object of the present invention to carry out goborotation in software, and to allow absolute position and velocitycontrol of the gobo rotation using a time slicing technique.

Another objective is to allow concentric-shaped images and unsupportedimages.

It is yet another object of the invention to provide a control systemfor the micromirror devices which allows such operation.

Yet another particularly preferred system is a shadowless follow spot,which forms an illuminating beam which is roughly of the same shape asthe performer, and more preferably precisely the same as the performer.The beam shape of the beam spot also tracks the performer's currentoutline. The spot light follows the performer as it lights theperformer. This action could be performed manually by an operator or viaan automated tracking system, such as Wybron's autopilot.

Since the beam does not overlap the performer's body outline, it doesnot cast a shadow of the performer.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects will be readily understood with reference to theaccompanying drawings, in which:

FIG. 1 shows a single pixel mirror element of the preferred mode, in itsfirst position;

FIG. 2 shows the mirror element in its second position;

FIG. 3 shows the mirror assembly of the present invention and itsassociated optics;

FIG. 4 shows more detail about the reflection carried out by the DMD ofthe present invention;

FIG. 5 shows a block diagram of the control electronics of the presentinvention;

FIG. 6 shows a flowchart of a typical operation of the presentinvention;

FIG. 7 shows a flowchart of operation of edge effects operations;

FIG. 8A shows a flowchart of a first technique of following a performeron stage;

FIG. 8B shows a flowchart of a correlation scheme;

FIG. 8C shows a flowchart of another correlation scheme;

FIG. 9A shows a block diagram of a color projection system of thepresent invention;

FIG. 9B shows a color wheel of the present invention;

FIG. 10 shows a block diagram of the shadowless follow spot embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment herein begins with a brief description ofcontrollable mirror devices, and the way in which thecurrently-manufactured devices operate.

Work on semiconductor-based devices which tune the characteristics oflight passing therethrough has been ongoing since the 1970's. There aretwo kinds of known digital micromirror devices. A first type wasoriginally called the formal membrane display. This first type used asilicon membrane that was covered with a metalized polymer membrane. Themetalized polymer membrane operated as a mirror.

A capacitor or other element was located below the metalized element.When the capacitor was energized, it attracted the polymer membrane andchanged the direction of the resulting reflection.

More modern elements, however, use an electrostatically deflected mirrorwhich changes in position in a different way. The mirror of the presentinvention, developed and available from Texas Instruments, Inc. uses analuminum mirror which is sputter-deposited directly onto a wafer.

The individual mirrors are shown in FIG. 1. Each individual mirrorincludes a square mirror plate 100 formed of reflective aluminumcantilevered on hollow aluminum post 45 on flexible aluminum beams. Eachof these mirrors 100 have two stop positions: a landing electrode, whichallows them to arrive into a first position shown in FIG. 2, and anotherelectrode against which the mirror rests when in its non-deflectedposition. These mirrors are digital devices in the sense that there two“allowable” positions are either in a first position which reflectslight to the lens and hence to the illuminated object, and a secondposition where the light is reflected to a scattered position. Lightscattering (i.e. selective light reflection) of this type could also bedone with other means, i.e. selectively polarizable polymers,electronically-controlled holograms, light valves, or any other means.

The operation of the dark field projection optics which is usedaccording to the preferred micromirror device is shown in FIG. 3. Thetwo bi-stable positions of the preferred devices are preferably plus orminus 10% from the horizontal.

An incoming illumination bundle 305 is incident at an arc of less than20° on the digital micomirror device 320. The illumination bounces offthe mirrors in one of two directions 326 or 335 depending on the mirrorposition. In the first direction 326, the position we call “on”, theinformation is transmitted in the 0 ° direction 326 towards lenses 330,332 which focus the information to the desired location 304. In thesecond direction of the mirror, the position we call “off”, theinformation is deflected away from the desired location to the direction335.

The human eye cannot perceive actions faster than about 1/30 second.Importantly, the mirror transit time from tilted left to tilted right ison the order of 10 Fs. This allows the pixels to be changed in operationmany orders of magnitude faster than the human eye's persistence ofvision.

Light source 310 used according to the present invention is preferably ahigh intensity light source such as a xenon or metal halide bulb ofbetween 600 and 1000 watts. The bulb is preferably surrounded by areflector of the parabolic or ellipsoidal type which directs the outputfrom bulb 300 along a first optical incidence path 305.

The preferred embodiment of the invention provides a color cross-fadingsystem 315, such as described in my U.S. Pat. No. 5,426,476.Alternately, however, any other color changing system could be used.This cross-fading system adjusts the color of the light. The lightintensity may also be controlled using any kind of associated dimmer;either electronic, mechanical or electromechanical means. Morepreferably, the DMD 320 could be used to control beam intensity asdescribed herein.

The light beam projected along path 305 is incident to the digital lightaltering device embodied as DMD 320, at point 322. The DMD allowsoperations between two different states. When the mirror in the DMD ispointed to the right, the right beam is reflected along path 335 toprojection/zoom lens combination 330, 332. The zoom lens combination330, 332 is used to project the image from the DMD 320 onto the objectof illumination, preferably a stage. The size and sharpness quality ofthe image can therefore be adjusted by repositioning of the lens. Whenthe mirror is tilted to the right, the light beam is projected along thelight path 335, away from projection lens 330/332. The pixels which havelight beams projected away from the lens appear as dark points in theresulting image. The dark spots are not displayed on the stage.

This DMD system reflects information from all pixels. Hence, minimalenergy is absorbed in the DMD itself or any of the other optics. Thedevice still may get hot, however not nearly as hot as the liquidcrystal gobos. Cooling 325 may still be necessary. The DMDs can becooled using any of the techniques described in (Bornhorst LCD), or by aheat sink and convection, or by blowing cold air from a refrigerationunit across the device. More preferably, a hot or cool mirror can beused in the path of the light beam to reflect infrared out of the lightbeam to minimize the transmitted heat. FIG. 3 shows hot mirror 321reflecting infra red 333 to heat sink 334. A cold minor would be usedwith a folded optical path.

This DMD system reflects information from all pixels. Hence, minimalenergy is absorbed in the DMD itself or any of the other optics. Thedevice still may get hot, however not nearly as hot as the liquidcrystal gobos. Cooling 325 may still be necessary. The DMDs can becooled using any of the techniques described in (Bornhorst LCD), or by aheat sink and convection, or by blowing cold air from a refrigerationunit across the device. More preferably, a hot or cool mirror can beused in the path of the light beam to reflect infrared out of the lightbeam to minimize the transmitted heat. FIG. 3 shows hot mirror 330reflecting infra red 332 to heat sink 334. A cold mirror would be usedwith a folded optical path.

This basic system allows selecting a particular aperture shape withwhich to which pass the light. That shape is then defined in terms ofpixels, and these pixels are mapped to DMD 320. The DMD selectivelyreflects light of the properly-shaped aperture onto the stage. The restof the light is reflected away,e.g., to a heat sink.

The micromirror can be switched between its positions in approximately10 μs. A normal time for frame refresh rate, which takes into accounthuman persistence of vision, is 1/60th of a second or 60 hertz. Variouseffects can be carried out by modulating the intensity of each mirrorpixel within that time frame.

The micromirror can be switched between its positions in approximately10 Fs. A normal time for frame refresh rate, which takes into accounthuman persistence of vision, is 1/60th of a second or 60 hertz. Variouseffects can be carried out by modulating the intensity of each mirrorpixel within that time frame.

The monolithic integration which is being formed by Texas Instrumentsincludes associated row and column decoders thereon. Accordingly, thesystem of the present invention need not include those as part of itscontrol system.

Detailed operation of DMD 320 is shown in FIG. 4. The source beam isinput to the position 322 which transmits the information either towardsthe stage along path 326 or away from the stage along path 335.

The various effects which are usable according to the present inventioninclude automatic intensity dimming, use of a “shadowless follow spot”,hard or soft beam edges, shutter cut simulation, gobo cross fading, gobospecial effects, stroboscopic effects, color gobos, rotating gobosincluding absolute position and velocity control, and other such effectsand combinations thereof. All of these effects can be controlled bysoftware running on the processor device. Importantly, thecharacteristics of the projected beam (gobo shape, color etc) can becontrolled by software. This enables any software effect which could bedone to any image of any image format to be done to the light beam. Thesoftware that is used is preferably image processing software such asAdobe Photoshop™, Kai's power Tools™ or the like which are used tomanipulate images. Any kind of image manipulation can be mapped to thescreen. Each incremental changes to the image can be mapped to thescreen as it occurs.

Another important feature of the gobo is its ability to projectunconnected shapes that cannot be formed by a stencil. An example is twoconcentric circles. A concentric circle gobo needs physical connectionbetween the circles. Other unconnected shapes which are capable ofrendering as an image can also be displayed.

The effects carried out by the software are grouped into three differentcategories: an edge effects processing; an image shape processing; and aduty cycle processing.

The overall control system is shown in block diagram form in FIG. 5.Microprocessor 500 operates based on a program which executes, interalia, the flowchart of FIG. 6. The light shape altering operatesaccording to a stencil outline. This stencil outline can be any image orimage portion. An image from image source 550 is input to a formatconverter 552 which converts the image from its native form into digitalimage that is compatible with storage on a computer. The preferreddigital image formats include a bitmap format or compressed bitmap formsuch as the GIF, JPEG, PCX format (1 bit per pixel) file, a “BMP” file(8 bits/pixel B/W or 24 bits/pixel color) or a geometric description(vectorized image). Moving images could also be sent in any animationformat such as MPEG or the like. It should be understood that any imagerepresentation format could be used to represent the image, and that anyof these representations can be used to create information that canmodify reflecting positions of the array of reflecting devices. Thepresent specification uses the term “digital representation” togenerically refer to any of these formats that can be used to representan image, and are manipulable by computers.

Image 554 is input into a working memory 556. BMP format represents each“pixel” picture element of the image by a number of bits. A typical grayscale bit map image has 8 bits representing each pixel. A colored imageof this type has 8 bits representing each of red, green, and bluerepresentations. This color representation is called a 24-bitrepresentation, since 24-bits are necessary for each pixel. Thedescription herein will be given with reference to gray scale imagesalthough it should be understood that this system can also be used withcolor images by forming more detailed maps of the information. Bit mapsare easiest to process, but extremely wasteful of storage space.

Each memory area, representing each pixel, therefore, has 8 bitstherein. The memory 556 is 576×768 area, corresponding to the number ofmirror elements in the preferred use.

This image is defined as image No. x, and can be stored in non-volatilememory 520 (e.g., flash RAM or hard disk) for later recall therefrom. Animportant feature of the present invention is that the images are storedelectronically, and hence these images can also be electronicallyprocessed in real time using image processing software. Since thepreferred mode of the present invention manipulates the imageinformation in bitmap form, this image processing can be carried out ina very quick succession.

The image to be projected is sent, by processor 500, over channel 560,to VRAM 570. Line driver 562 and line receiver 564 buffer the signal atboth ends. The channel can be a local bus inside the lamp unit, or canbe a transmission line, such as a serial bus. The image information canbe sent in any of the forms described above. Standard and commonlyavailable image processing software is available to carry out manyfunctions described herein. These include for example, morphing,rotating, scaling, edge blurring, and other operations that aredescribed herein. Commercial image processing can use “Kai's PowerTools”, “CorelDraw!”, or “Morph Studio” for example. These functions areshown with reference to the flowchart of FIG. 6.

Step 600 represents the system determining the kind of operation whichhas been requested: between edge processing, image processing, and dutycycle processing. The image processing operations will be defined first.Briefly stated, the image processing operations include rotation of theimage, image morphing from image 1 to image 2, dynamic control of imageshape and special effects. Each of these processing elements can selectthe speed of the processing to effectively time-slice the image. Themorphing of the present invention preferably synchronizes keyframes ofthe morph with desired time slices.

Step 602 defines the operation. As described above, this operation caninclude rotation, position shift, and the like. Step 604 defines thetime or velocity of operation. This time can be ending time for all orpart of the movement, or velocity of the movement. Note that all of theeffects carried out in step 602 require moving some part of the imagefrom one position to another.

Step 606 determine the interval of slicing, depending on the velocity.It is desirable to slice an appropriate amount such that the user doesnot see jerky motion. Ideally, in fact, we could slice movement of theimage one pixel at a time, but this is probably unnecessary for mostapplications. One hundred pixel slicing is probably sufficient for allapplications. The pixel slices are selected at step 606.

Step 608 calculates using the time or velocity entered at step 604 todetermine the necessary time for operation based 25 on the amount ofposition shift for rotation over 100 pixel slices. This is done asfollows. Position shift, rotation, and sprite animation are all simplemovements. In both, the points of the image which define the gobo shapemove_over time. It is important, therefore, to decide how much movementthere is and how much time that movement will take. A rate of change ofpoints or velocity is then calculated. Of course velocity need not becalculated if it has already been entered at step 604.

Having velocity of movement and pixels per second, the time betweenslices is calculated using 100 pixels per slice divided by the velocityin pixels per second. The direction of movement is defined by thisoperation.

Therefore, the image is recalculated at step 610 for each time interval.This new image becomes the new gobo stencil at the new location. That isto say, the outline of the image is preferably used as the gobo—lightwithin the image is passed, and light outside the image is blocked. Inthe color embodiment described herein, more sophisticated operations canbe carried out on the image. For example, this is not limited to stencilimages, and could include for example concentric circles or letter textwith font selection.

At any particular time, the image in the VRAM 570 is used as the gobostencil. This is carried out as follows. Each element in the image is agray scale of 8-bits. Each 1/60th of a second is time-sliced into 256different periods. Quite conveniently, the 8-bit pixel image correspondsto 28=256.

A pixel value of 1 indicates that light at the position of the pixelwill be shown on the stage. A pixel value of zero indicates that lightat the position of the pixel will not be shown on the stage. Any grayscale value means that only part of the intensity pixel will be shown(for only part of the time of the 1/60th of a second time slice). Hence,each element in the memory is applied to one pixel of the DMD, e.g. oneor many micromirrors, to display that one pixel on the stage.

When edge processing is selected at step 600, control passes to theflowchart of FIG. 7. The edge graying can be selected as either agradual edge graying or a more abrupt edge graying. This includes onearea of total light, one area of only partial light, and one area of nolight. The intensity of the gray scaled outline is continuously gradedfrom full image transmission to no image transmission. The intensityvariation is effected by adjusting the duty cycle of the on and offtimes.

Step 700 obtains the image and defines its outlines. This is carried outaccording to the present invention by determining the boundary pointbetween light transmitting portions (1's) and light blocking portions(0's). The outline is stretched in all directions at step 702 to form alarger but concentric image—a stretched image.

The area between the original image and the stretched image is filledwith desired gray scale information. Step 704 carries this out for allpoints which are between the outline and the stretched image.

This new image is sent to memory 570 at step 706. As described above,the image in the memory is always used to project the image-shapedinformation. This uses standard display technology whereby the displaysystem is continually updated using data stored in the memory.

The duty cycle processing in the flowchart of FIG. 6 is used to formstrobe effects and/or to adjust intensity. In both cases, the image isstored in memory and removed from memory at periodic intervals. Thisoperation prevents any light from being projected toward the stage atthose intervals, and is hence referred to as masking. When the image ismasked, all values in the memory become zero, and hence this projectsall black toward the source. This is done for a time which is shorterthan persistence of vision, so the information cannot be perceived bythe human eye. Persistence of vision averages the total light impingingon the scene. The eye hence sees the duty cycle processing as adifferent intensity.

The stroboscopic effect turns on and off the intensity, ranging fromabout 1 Hz to 24 Hz. This produces a strobe effect.

These and other image processing operations can be carried out: (1) ineach projection lamp based on a pre-stored or downloaded command; (2) ina main processing console; or (3) in both.

Another important aspect of the invention is based on the inventor'srecognition of a problem that has existed in the art of stage lighting.Specifically, when a performer is on the stage, a spotlight illuminatesthe performer's area. However, the inventor of the present inventionrecognized a problem in doing this. Specifically, since we want to seethe performer, we must illuminate the performer's area. However, when weilluminate outside the performer's area, it casts a shadow on the stagebehind the performer. In many circumstances, this shadow is undesirable.

It is an object of this embodiment to illuminate an area of the stageconfined to the performer, without illuminating any location outside ofthe performer's area. This is accomplished according to the presentinvention by advantageous processing structure which forms a “shadowlessfollow spot”. This is done using the basic block diagram of FIG. 10.

The preferred hardware is shown in FIG. 10. Processor 1020 carries outthe operations explained with reference to the following flowchartswhich define different ways of following the performer. In all of theseembodiments, the shape of the performer on the stage is determined. Thiscan be done by (1) determining the performer's shape by some means, e.g.manual, and following that shape; (2) correlating over the image lookingfor a human body shape; (3) infra red detection of the performer'slocation followed by expanding that location to the shape of theperformer; (4) image subtraction; (5) detection of special indices onthe performer, e.g. an ultrasonic beacon, or, any other technique evenmanual following of the image by, for example, an operator following theperformer's location on a screen using a mouse.

FIG. 8A shows a flowchart of (1) above. At step 8001, the performer islocated within the image. The camera taking the image is preferablylocated at the lamp illuminating the scene in order to avoid parallax.The image can be manually investigated at each lamp or downloaded tosome central processor for this purpose.

Once identified, the borders of the performer are found at 8005. Thoseborders are identified, for example, by abrupt color changes near theidentified point. At step 8010, those changes are used to define a“stencil” outline that is slightly smaller than the performer at 8010.That stencil outline is used as a gobo for the light at 8015.

The performer continues to move, and at 8020 the processor follows thechanging border shape. The changing border shape produces a new outlinewhich is fed to 8010 at which time a new gobo stencil is defined.

Alternative (2) described above is a correlation technique. A flowchartof this operation is shown in FIG. 8B. At step 8101, the camera obtainsan image of the performer, and the performer is identified within thatimage. That image issued as a kernel for further later correlation. Theentire scene is obtained at step 8105. The whole scene is correlatedagainst the kernel at 8110. This uses known image processing techniques.

The above can be improved by (3), wherein infra red detection gives theapproximate area for the performer.

As explained in previous embodiments, the DMD is capable of updating itsposition very often: for example, 106 times a second. This is muchfaster than any real world image can move. Thirty times a second wouldcertainly be sufficient to image the performer's movements. Accordingly,the present invention allows setting the number of frame updates persecond. A frame update time of 30 per second is sufficient for mostapplications. This minimizes the load on the processor, and enables lessexpensive image processing equipment to be used.

FIG. 8C shows the image subtracting technique.

First, we must obtain a zeroing image. Therefore, the first step at step800, is to obtain an image of the stage without the performer(s)thereon. This zero image represents what the stage will look like whenthe performers are not there.

Between processing iterations, the processor can carry out otherhousekeeping tasks or can simply remain idle.

Step 802 represents the beginning of a frame update. An image isacquired from the video camera 550 at step 804. The image is stillpreferably arranged in units of pixels, with each pixel including avalue of intensity and perhaps red, green, and blue for that pixel.

At step 806 subtracts the current image from the zeroed image. Theperformer image that remains is the image of the performer(s) and othernew elements on the stage only. The computer determines at this timewhich part of that image we want to use to obtain the shadowless followspot. This is done at step 808 by correlating the image that remainsagainst a reference, to determine the proper part of the image to beconverted into a shadowless follow spot. The image of the performer isseparated from other things in the image. Preferably it is known forexample what the performer will wear, or some image of a uniquecharacteristic of the performer has been made. That uniquecharacteristic is correlated against the performer image to determinethe performer only at the output of step 808. This image is digitized atstep 810: that is all parts of this image which are not performer areset to zeros so that light at those positions is reflected. In this way,a gobo-like image is obtained at step 810, that gobo-like image being achanging cutout image of the performer. An optional step 812 furtherprocesses this image to remove artifacts, and preferably to shrink theimage slightly so that it does not come too close to the edge of theperformer's outline. This image is then transferred to the VRAM at step814, at which time it is re-entered into the DMD 1012 to form agobo-like mask for the lamp. This allows the light to be appropriatelyshaped to agree with the outline of the performer 1004.

Another embodiment of the present invention uses the above describedtechniques and basic system of the present invention to provide color tothe lamp gobo. This is done using techniques that were postulated in theearly days of color TV, and which now find a renewed use. This systemallows colored gobos, and more generally, allows any video image to bedisplayed.

FIG. 9A shows the lamp 310 in a series with a rotating multicolored disk902. FIG. 9B shows the three sectors of the disk. Red sector 950, a bluesector 952, and a green sector 954. The light along the optical path 904is colored by passing through one of these three quadrants, and thenthrough DMD 320. DMD 320 is driven by a video source 910, synchronizedwith the operation of spinning of the color disk 902. The DMD is drivenby the video is driven to produce a red frame, then a green frame, thena blue frame, one after another, for example. The red filtered video istransferred at the same moment when the red sector 950 is in the lightpath. So as long as the different colors are switched faster than theeye's persistence of vision, the eye will average them together to see afull color scene.

Although only a few embodiments have been described in detail above,those having ordinary skill in the art will certainly understand thatmany modifications are possible in the preferred embodiment withoutdeparting from the teachings thereof.

All such modifications are intended to be encompassed within thefollowing claims.

For example, any direction deflecting device could be used in place ofthe DMD. A custom micro mirror device would be transparent, and havethin mirrors that “stowed” at 90° to the light beam to allow the beam topass, and turned off by moving to a reflecting position to scatterselect pixels of the light beam. The color changing devices could be anydevice including dichroics.

1. A method of shaping a light beam, comprising: receiving an image;storing said image in a memory; and using said image in said memory asan outer stencil to shape an outer perimeter of a projected beam oflight such that light is projected with said outer stencil, andsubstantially no light is projected outside said outer stencil.
 2. Amethod as in claim 1, further comprising changing the image, in saidmemory, wherein said using comprises automatically changing a projectedperimeter as the image changes.
 3. A method as in claim 2, wherein saidchanging comprises changing said image at periodic intervals.
 4. Amethod as in claim 3, wherein said changing comprises changing the imageby a specified number of pixels per interval of time.
 5. A method as inclaim 4, wherein said specified number of pixels is 100 pixels.
 6. Amethod as in claim 2, further comprising masking said image at specifiedtimes to prevent projection of said beam of light, said maskingoccurring at times between two projections of images.
 7. A method as inclaim 1, further comprising masking said image at specified times, toprevent projection of said beam of light.
 8. A method as in claim 1,further comprising processing the image, to change an aspect of theimage, said changing causing the outer perimeter of the projected beamof light to automatically change.
 9. A method as in claim 8, furthercomprising projecting using a lamp, wherein said image processing iscarried out in a device which is in a remote location from said lamp.10. A method as in claim 1, wherein said memory is a video random-accessmemory.
 11. A method of shaping a light beam, comprising: receivinginformation indicative of multiple images which change over time; at afirst time, storing a first of said multiple images in a memory, andusing said first image in said memory as a first outer stencil to shapean outer perimeter of a first projected beam of light such that light isprojected with said first outer stencil, and substantially no light isprojected outside said first outer stencil; and at a second time,storing a second of said multiple images in said memory, and using saidsecond image in said memory as a second outer stencil to shape an outerperimeter of a second projected beam of light such that light isprojected with said second outer stencil, and substantially no light isprojected outside said second outer stencil.
 12. A method as in claim11, wherein said memory is a video random-access memory.
 13. A method asin claim 11, wherein said first and second images are only keyframes.14. A lighting apparatus, comprising: a receiver, receiving informationindicative of an image; a memory, storing said image; and a lightprojecting gate, using said image in said memory as an outer stencil toshape an outer perimeter of a projected beam of light such that light isprojected with said outer stencil, and substantially no light isprojected outside said outer stencil.
 15. An apparatus as in claim 14,further comprising a light source, projecting a beam that is shaped bysaid light projecting gate.
 16. An apparatus as in claim 14, furthercomprising an image processor, changing the image in said memory, andautomatically changing a projected perimeter as the image changes. 17.An apparatus as in claim 14, further comprising a controller, maskingsaid image at specified times, to prevent projection of said beam oflight.
 18. An apparatus as in claim 14, wherein said memory is a videorandom-access memory.